The incidence and prevalence of end-stage renal disease is increasing at an alarming rate, new innovative therapies for halting the progress of chronic renal failure are urgently demanded. Overexpression of transforming growth factor-beta 1 (TGF[unreadable]1) is the most common molecular feature of progressive renal disease. It has been identified as a primary key mediator and quantifiable measure of fibrotic renal disease. TGF[unreadable]1 appears to be a promising target for treatment of chronic renal disease. However, that TGF[unreadable] has profound anti-inflammatory properties and that animals genetically deficient in TGF[unreadable] die of overwhelming inflammation shortly after birth, raises the possibility that systemic TGF[unreadable] blockade may have serious inflammatory side effects. All human clinical trials of TGF[unreadable] blockade are unfortunately hampered by its potential systemic side effects. Targeted delivery of TGF[unreadable] blockade to fibrotic glomeruli offers novel therapeutic approaches for treatment without noteworthy systemic adverse effects. By combining small interfering RNA (siRNA) with nanoparticle technology, we have recently developed a mesangial cell-specific, ligand-targeting, self- assembled siRNA-nanovector system for gene delivery. The nanovectors show promising efficiency and specificity in targeted delivery of siRNA against the renin receptor gene to nephritic glomeruli in rat, with limited effect on other tissues. The objective of this R21 exploratory project proposal is to explore the feasibility of using our novel nanovector system for mesangial cell targeted nanoparticle-based siRNA therapeutics for glomerular fibrosis. We propose to use TGF[unreadable]1-Steath siRNA to test two inter-related hypotheses: (1) the self- assembled nanovectors can selectively deliver siRNA to glomerular mesangial cells and efficiently silence the target TGF[unreadable]1;(2) Specifically silencing of TGF[unreadable]1 in glomerular mesangial cells will ameliorate the progression of matrix expansion in experimental glomerulonephritis. Our long-term goal is to develop the mesangial cell- targeting nanoparticle-based siRNA as novel molecular therapy for glomerular disease. To test our hypothesis, we propose to carry out two Specific Aims: Aim 1: To prepare and optimize nanovectors for efficient knock- down of TGF[unreadable]1 gene expression by RNA interference both in vitro and in vivo;Aim 2: To investigate the in vivo therapeutic potential of nanovector-delivered RNAi in experimental glomerulonephritis where high levels of TGF[unreadable]1 occur locally in glomeruli. Successfully carried out, our study will provide proof-of-concept that siRNA can be selectively delivered to mesangial cells by the self-assembled nanovectors. This novel strategy will be critical for the studies in glomerular fibrosis development and progression. It also will have a significant impact on the development of a glomerulus-targeted anti-TGF[unreadable]1 siRNA molecule as a novel adjuvant therapy to overcome systemic adverse effects for glomerular fibrosis but overcomes systemic adverse effects that may help combat the current epidemic in chronic kidney disease. PUBLIC HEALTH RELEVANCE: TGF[unreadable]1, as a promising target for treatment of chronic renal disease, has profound anti-inflammatory properties, which may hamper all clinical trials of systemic TGF[unreadable]1 blockade. By combining small interfering RNA (siRNA) with nanoparticle technology, we have recently developed a mesangial cell-specific, ligand- targeting, self-assembled siRNA-nanovector system for gene delivery. The nanovectors show promising efficiency and specificity in targeted delivery of siRNA against the renin receptor gene to nephritic glomeruli in rat, with limited effect on other tissues. The objective of this R21 exploratory project proposal is to explore the feasibility of using our novel nanovector system for mesangial cell targeted nanoparticle-based anti-TGF[unreadable]1 siRNA therapeutics for glomerular fibrosis. We propose to (1) prepare and optimize nanovectors for efficient knockdown of TGF[unreadable]1 gene expression by RNA interference in vitro and in vivo;(2) investigate the in vivo therapeutic potential of nanovector-delivered RNAi in experimental glomerulonephritis where high levels of TGF[unreadable]1 occur locally in glomeruli. Successfully carried out, our studies will have a significant impact on the development of an organ-targeted anti-TGF[unreadable]1 siRNA molecule as a novel adjuvant therapy for glomerular fibrosis but overcomes systemic adverse effects that may help combat the current epidemic in chronic kidney disease.